/**
 * Register the portable DSH Plugin Development Skill with the Harness registry.
 *
 * The package ships plain JavaScript so Git and tarball installations need no
 * install-time build script. The skill body and its relative resources remain
 * files in the package for on-demand loading by the agent.
 */

import { readFileSync } from 'node:fs'
import { dirname } from 'node:path'
import { fileURLToPath } from 'node:url'

const SKILL_FILE_URL = new URL('./skills/dsh-plugin-development/SKILL.md', import.meta.url)
const SKILL_FILE = fileURLToPath(SKILL_FILE_URL)
const SKILL_DIRECTORY = dirname(SKILL_FILE)
const FRONTMATTER = /^---\r?\n([\s\S]*?)\r?\n---\r?\n/

export const name = 'dsh-plugin-development'
export const inject = ['skills']

function readFrontmatterScalar(frontmatter, key) {
  const line = frontmatter.split(/\r?\n/).find(candidate => candidate.startsWith(`${key}:`))
  if (line === undefined) throw new Error(`dsh-plugin-development: packaged SKILL.md has no ${key}`)
  const value = line.slice(key.length + 1).trim()
  if (value.startsWith("'") && value.endsWith("'")) return value.slice(1, -1).replaceAll("''", "'")
  if (value.startsWith('"') && value.endsWith('"')) return JSON.parse(value)
  if (value === '') throw new Error(`dsh-plugin-development: packaged SKILL.md has an empty ${key}`)
  return value
}

function readSkill() {
  const source = readFileSync(SKILL_FILE, 'utf8').replace(/^\uFEFF/, '')
  const match = FRONTMATTER.exec(source)
  if (match === null) throw new Error('dsh-plugin-development: packaged SKILL.md has no valid frontmatter block')
  return {
    name: readFrontmatterScalar(match[1], 'name'),
    description: readFrontmatterScalar(match[1], 'description'),
    content: source.slice(match[0].length).replace(/^\r?\n/, ''),
  }
}

/** Register the packaged skill as a reversible runtime contribution. */
export function apply(ctx) {
  const skill = readSkill()
  ctx.skills.register({
    ...skill,
    source: 'bundled',
    provider: 'dsh-plugin-development',
    resourceBase: { kind: 'directory', path: SKILL_DIRECTORY },
    path: SKILL_FILE,
  })
}